Adenomatous colon polyps

Adenomatous colon polyps

    * Introduction
    * Causes
    * Signs and symptoms
    * Diagnosis
    * Treatment
Neoplastic adenomatous polyps are by definition. Although the direct precursors of adenocarcinomas are benign and malignant follow a trend if not treated.
Polyps are usually asymptomatic but can occasionally cause bleeding and ulcers, rarely cause bowel obstruction. Immediate risk of adenomas is the bleeding, obstruction, and torsion intussusceptie. The risk of colonic adenomatosis people to develop carcinoma in situ is 4 times higher than in the general population.
Vilo Adenomas represent 80% of all adenomatous polyps histological forms and presents the greatest risk of malignancy of 15-25%. The risk of adenocarcinoma is approaching 40% for Vilo tumors larger than 4 cm in diameter. Patients with rectosigmoid adenomas larger than 1 cm or histology viloasa carcinoma had a risk of 3-6 times higher than in the general population.
Vilo Adenomas of Vater's ampoule contain carcinoma in 30-50% of cases and 20-25% in the duodenum. The prevalence of adenomas increases with age. Prevalence at age 50 is 30%, 60% 40-50 years and 70 years of 50-60%. Distribution of polyps varies depending on age. In patients 55 years or younger, 75% of polyps are 10mm or larger and are located distally. In patients 65 years or older were 50% of polyps 10mm or larger, are located proximally.
Colonoscopy is a screening procedure to detect persons with colonic adenomas. If possible resection by endoscopy will be sent to all polyps and for histopathology examination to confirm or rule out malignancy, the degree of dysplasia and histological type.
Cauterisation resection is indicated for large polyps. Surgical resection is necessary when large polyps 2-3 cm and if sessile. If spread over a large area and are very numerous segmental colotomia is indicated. Depending on the nature of colonic adenomas in patients requiring colonoscopy surveillance after initial therapy to capture the early development of other polyps or carcinomas.
Pathogenesis
Adenomatous polyps are not cancerous. They follow a mandatory malignant evolution within 10 years. Can be stem or sessile. Sessile polyps are more dangerous than the pedunculate two reasons. First, the route of migration of tumor cells in the submucosa invasive and more remote structures is shorter. The second reason is the difficulty implied by their endoscopic resection. It is divided into three histological subtypes: tubular and vilosi tubulovilosi. After the criteria established by the World Health Organization, Vilo adenomas are composed of over 80% viloasa architecture. Tubular adenomas are the most common 80%.
It is believed that adenomas shows abnormal processes of cell proliferation and apoptosis. Progression to carcinoma is final in four years. A third of colon cancers are caused synchronous. Increased colon cancer risk is proportional to the greater number of adenomatous polyps.
Molecular and genetic studies showed an adenoma-carcinoma sequence by accumulating mutations in a variety of genes with activation of oncogenes and inactivation of tumor suppressor genes. Genetic mutations leading to alterations of cellular DNA. The genes involved are K-RAS, APC, TP53.
Vilo adenomas are most commonly associated with large and severe degrees of dysplasia. They occur more frequently in the rectal area and rectosigmoidian, but can be found anywhere on the colon. They are generally sessile structures that resemble the folds of velvet or macroscopic petals of a flower. Although rare, it can discover the small intestine and duodenal adenomas, particularly of the ampoule. Vilo adenomas are the most dangerous due to increased risk of malignancy.